In general, this invention relates to digital data processing; more particularly, it relates to a method and apparatus using a data-dependent boundary-marking code word to partition data into cells.
A single binary digit (bit) has only two possible values and, accordingly, by itself can represent very little information. A plurality of bits can be grouped in a predetermined order to represent much more information. As one representative example, four bits can be grouped in a most-significant-bit to least-significant-bit order to provide for representing any one of the sixteen hexidecimal digits "O" to "F".
Such a four-bit grouping is one type of "byte-size" grouping. Bytes of 4 bits or 8 bits are very commonly used as elements, in a hierarchical grouping of bits, to provide for representing an even larger amount of information.
In processing information, it is necessary to ensure consistency in the ordering of bits composing a group that is to be processed at different times or by different communicating subsystems. One common approach directed to ensuring such consistency employs a unique marker that identifies a boundary of a multi-bit cell. Such a marker has been defined by a pulse signal differing in amplitude or duration from the type of signal used to represent a data bit. Such a marker has also been defined by a sequence of bits composing a code word that is fixed in that every cell contains the same code word as its boundary marker.